Knit elastic mesh loop pile fabric for orthopedic and other devices

ABSTRACT

An improved fabric for orthopedic devices is provided, being a knitted fabric produced on either a warp or weft knit system and utilizing a filament yarn selected from nylon and polyester as well as spandex. The fabric enhances freedom of movement while stimulating blood flow and muscle tone. The fabric has an elasticity that enables closure of orthopedic and other devices by placing the hook component of a Velcro (®) strip at any convenient point rather than aligning it with the loop component of the Velcro (®). The fabric is more convenient, faster and easier for many incapacitated persons, enhancing wearing comfort. Its mesh structure makes it more porous, which enhances the air circulation and the moisture management in creating a cooling effect on the wearer&#39;s skin and ready evaporation of perspiration, while still providing therapeutic warmth without heat buildup.

This application claims priority benefit of U.S. Provisional Application No. 60/847,186 filed Sep. 26, 2006. The subject application is also related to the following applications:

-   Fabric for Protection against Electric Arc Hazards -   60/847,305 filed Sep. 26, 2006 U.S. patent application Ser. No.     ______ filed ______, -   Under Body Armor Cooling Vest and Fabric Thereof -   60/847,307 filed Sep. 26, 2006 U.S. patent application Ser. No.     ______ filed ______, and -   Improved High Performance Fire Resistant Fabrics and the Garments     Made Therewith -   60/847,002 filed Sep. 25, 2006; U.S. patent application Ser. No.     ______ filed ______.

BACKGROUND OF THE INVENTION

The invention relates to a knit fabric, and, more particularly, to an elastic knit fabric having a loop pile construction.

Orthopedic devices such as braces, splints, supports, orthodics, slings, bandaging, etc. are used to relieve discomfort, pain, physical weakness for diverse conditions, ailments or rehabilitative convalescence, such as osteoporosis, osteoarthritis, tendonitis, sprains, bone fractures, chronic lower back pain, compression fractures, degenerative disc disease, post operative fusion, spinal tenosis (spinal narrowing), scoliosis (lateral curvature of the spine), lumbar orthosis (spinal rectification) and a number of others, each requiring a specialized aid or device. These devices must be comfortable, lightweight, low profile, patient friendly and suited for the daily living activities and sedentary lifestyles for many afflicted persons.

Orthopedic devices consist essentially of several parts including, but not limited to, a foam or rubber cushion, a fabric covering, and supporting or adjustment straps, the latter of which may carry buckles or Velcro (®) closure systems. A layer of film, such as a non-woven or fibrous batting, may also be included in some devices.

Velcro (®) closure systems are in many cases preferable to others due to their simplicity, ease of use and faster engagement or disengagement of component parts.

The cushioning material may be either neoprene rubber, a non-woven material, a spacer fabric (a resilient 3-D fabric) or some kind of foam. Neoprene, while cheap and in frequent use, has poor air porosity, which leads to heat buildup, inducing perspiration and discomfort.

There is a number of foam products available on the market which are suitable for orthopedic applications. One of the better known is the Rubberlite (®) product manufactured by the Rubberlite Corp. of Huntington, W. Va. This foam is breathable, stretchable, thermally formable and provides a controlled degree of cushioning. This is an open celled polyurethane foam that can be provided with an anti-microbial additive. It is, however, disadvantageous since the foam does not sufficiently control the amount of perspiration generated along a patient's skin. Such perspiration must be removed from the skin and evaporated if a feeling of clamminess is to be avoided. Also the Rubberlite foam is less than desirable due to its tendency to break down and disintegrate.

The components of orthopedic devices are held together and in proper position on a patient's body by a system of engineered designed straps engaged with each other through the action of Velcro (®) type closures where the hook members of one strap engage the loop pile of its mating strap. This requires mating of both members.

The loop pile of the Velcro (®) closure may be either woven or warp knit. The latter is softer and more pliable than the woven variety. The warp knit product also has a significant amount of useful give or extensibility. In most cases, the warp knit pile is generated by a napping process, which raises the fabric floats into a system of dense, erect loops. It is also possible to produce such a pile without the process of napping by directly knitting the surface loops. The same applies to circular knit fabrics of the surface loop type:

In most cases, orthopedic devices are made with neoprene rubber foam laminated to either a woven or knit fabric; they also utilize Velcro (®) type closures for holding the devices in place. Neoprene rubber foam carries the functional disadvantages outlined above. Also, woven fabrics have low permeability to air and do not conform well to the contours of a patient's body or limbs.

Further, the Velcro (®) straps must be carefully aligned and mated to effect a secure closure and correct fit of the orthopedic device involved. Thus, the fabrics in current use have limited flexibility and give, thereby constraining the freedom of movement.

Accordingly, it would be desirable to provide an improved fabric for use in orthopedic devices that overcomes the above disadvantages.

SUMMARY OF THE INVENTION

In accordance with the invention, an improved fabric for orthopedic devices is provided. The inventive fabric is a knitted fabric produced on either a warp or weft knit system. The fabric is knit utilizing a filament yarn selected from nylon and polyester as well as spandex having an elongation at break of between about 300% and 700%. The fabric is knit so as to have a mesh construction with a pore size of between about 1 and 3 mm. in diameter. Importantly, the inventive knit fabric has a loop pile construction generated along one side thereof.

Other applications of the fabric according to the present invention include backpack and footwear components working in conjunction with the Velcro (®) closure system where the male parts thereof engage the loop pile of the fabric to effect the closure.

The improved fabric of the invention is advantageous since:

-   -   1) the spandex content enhances the freedom of movement while         stimulating blood flow and muscle tone;     -   2) its elasticity enables closure of orthopedic and other         devices by placing the hook component of the Velcro (®) strip at         any convenient point rather than aligning it with the loop         component of the Velcro (®); this is much more convenient,         faster and easier for many incapacitated persons and also         enhances the wearing comfort; and     -   3) the mesh structure makes it more porous, which enhances the         air circulation and the moisture management in creating a         cooling effect on the wearer's skin and ready evaporation of         perspiration, while still providing therapeutic warmth without         heat buildup.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the inventive fabric.

DETAILED DESCRIPTION OF THE INVENTION

The fabric of the present invention may be produced on either warp or weft (circular) basis. However, a warp, in particular, a fine gauge tricot, is more facile in manufacture and generally produces a better fabric. This is because a warp knit system lends itself better to the formation of mesh structures than does a circular knit system. In particular, warp knit meshes may be produced without any special auxiliary elements, while circular knit meshes require special knitting elements during production; such elements are cumbersome to use and detract from knitting efficiency.

There are a number of ways to generate an upstanding loop pile for the inventive fabric. It may be accomplished by overfeeding the warp threads so that the excess yarns are not incorporated in the fabric structure collect on its surface in order to form a loop pile effect. It may also be accomplished with the aid of special loop forming elements such as using special sinkers, points or blades, which manipulate the warp threads or stitch components into a loop pile.

It may further be accomplished by employing the knitting technique of releasing (pressing off) the surface loops using stitch combination whereby certain stitches are drawn on one course and then released or “pressed off” on the next course so as to create a loop pile.

In the present invention, the fabric responds especially well to a napping procedure, which is the preferred method for generating a loop pile along one surface of the inventive fabric. This results in the well known UBL (unbroken loop) velvet-like fabric extensively used in apparel, footwear and Velcro (®) closure systems. In particular, the yarn floats on the technical reverse side of the inventive fabric are produced by thread members connecting the wales. These yarn floats are disposed along the surface of the fabric and become engaged during the process of napping by the napper wires in order to produce a raised unbroken loop pile. The length of the floats may be varied through appropriate construction design of the inventive fabric.

Here, the yarn floats of the technical reverse side of the tricot fabric are engaged by the napper wire and raised into an unbroken loop pile in a closely controlled process. Napping produces a soft, dense pile that is very compatible with the hook members of the Velcro (®) closures and which is able to withstand multiple open and close cycles.

Importantly, the napping procedure satisfies the stringent requirements of the Velcro (®) closures. These stringent requirements of the Velcro closure are:

-   -   1. the loop pile should be of uniform height;     -   2. the loops should be firmly anchored in the fabric base; and     -   3. the loops should be strong enough to withstand the stresses         and strains of repeatedly opening and closing closure elements         without failure and fraying of the loop filaments.

The mesh construction of the inventive fabric is produced during knitting. The mesh construction of the inventive fabric increases the permeability of air so as to enhance the wearing comfort by facilitating evaporation of perspiration and dissipating skin heat buildup. A mesh construction is produced when there is no connection between adjacent wales for one or more courses. When this occurs, the tension inside the knit structure of the fabric pulls the adjacent wales so as to form a mesh opening.

The mesh openings should have a mesh count of between about 5 and 8 meshes/inch in the width and between about 4 and 6 meshes/inch in the length.

In accordance with the invention, the filament yarns are present in the inventive fabric in an amount of between about 85 and 95 weight percent and are blended with spandex present in the inventive fabric in an amount between about 5 and 15 weight percent of the fabric in order to impart the requisite amount of stretch. In other words, the spandex yarns are knitted together with the filament yarns to provide the inventive fabric with stretch in both the width and the length. In the width, the fabric of the invention has a stretch of between about 75% and 125%, while in the length the stretch is between about 25% and 60%.

Almost any filament yarn of medium tenacity (between about 4 and 7 gram per denier) may be used here. The filament yarns should have a denier of between about 40 and 70 and the number of filaments per yarn is between about 10 and 24. However, nylon filament is the preferred fiber because of its moisture, absorption, pleasant touch against the skin, good response to the napping process, ease of dyeing and resilience in Velcro (®) action thanks to the elastic recovery of this fiber. Polyester yarn is another option where lower cost and greater choice of yarn sizes and filament counts are predominant considerations.

In the fabric embodiment described below, the yarns used are 40 denier 12 filament nylon and 40/1 denier clear spandex yarn which imparts the fabric its stretch and recovery characteristics. In general, the spandex yarn used in the inventive fabric will have a denier between about 40 and 70.

Any one skilled in the art can specify a yarn system for a specific consideration of fabric performance and economics. What is meant by performance is the amount of pull or separating force the Velcro (®) is designed to withstand, which depends on application is sporting, orthopedic, industrial or other devices.

Only one example of warp knit (tricot) fabric is provided. Anyone skilled in the art can generate many constructional permutations and combinations of yarn and stitch systems, which are a matter of choice. The same applies to the choice of equipment, its gauge (needles per inch), stitch configuration and processing sequence.

EXAMPLE 1

One type of fabric of the invention is manufactured utilizing a 4 guide bar, 28 gauge (28 needles/inch), tricot.

The yarns and their location relative to the guide bars used in manufacture of the fabric of Example 1 are detailed below:

Bar 1 (Back) 40/1 clear Spandex 29 inch runner Bar 2 40/12 den Nylon 6, bright trilobal 50 inch runner Bar 3 40/12 den Nylon 6, bright trilobal 50 inch runner Bar 4 (Front) 40/12 den Nylon 6, bright trilobal 91 inch runner

Bars 2 and 3 create the mesh structure of the fabric, while bar 4 produces long floats suitable for napping.

The threading chart for Example 1 is as follows:

Bar 1 (back) .......|||||||||| .|||||.||||| |||||................... Bar 2 ....||||||||||||| .||||||||||| ||...................... Bar 3 .........|||||||| .||||||||||| |||||||................ Bar 4 (front) ................. ...||||||||| .......................

The stitch construction for Example 1 is as follows:

BAR 1 BAR 4 (Back) BAR 2 BAR 3 (Front) 1-0 7-8 1-0 1-0 1-2 7-6 1-2 3-4 7-8 1-0 1-0 7-6 1-2 3-4 6-5 2-3 1-0 5-4 3-4 3-4 4-3 4-5 6-7 3-2 5-6  9-10 2-1 6-7 7-6 1-0 7-8  9-10 1-2 7-6 7-6 1-0 7-8  9-10 1-2 7-6 7-6 2-3 6-5  9-10 3-4 5-4 7-6 4-5 4-3 4-3 5-6 3-2 1-0 6-7 2-1 3-4

The parameters for the fabric of Example 1 are as follows:

Fabric width 60 inch Fabric weight 7.35 oz/yd. sq. +5% Hand stretch 40% in length Shrinkage 5% in length and width Courses 72 per inch Wales 52 per inch Elongation at break 40%

The fabric of Example 1 is jet dyed and napped on its technical back.

The fabric of Example 1 may also be either napped or sueded on its technical face in order to enhance its adhesion in bonding to the foam material of the orthopedic device.

The scope of the invention will now be set forth in the following claims. 

1. A knit fabric comprising: filament yarns selected from yarns of the group consisting of nylon yarns and polyester yarns and present in an amount between about 85 and 95% weight percent; spandex yarns integrally knit with the filament yarns in an amount between about 5 and 15 weight percent; wherein the fabric has a mesh construction; wherein the fabric has a loop pile construction along one side thereof.
 2. The fabric of claim 1, wherein the filament yarns comprise nylon yarns.
 3. The fabric of claim 1, wherein the spandex yarns have an elongation at break of between about 300% and 700%.
 4. The fabric of claim 1, wherein the mesh construction of the fabric defines a plurality of openings, each having a pore size of between about 1 and 3 mm. in diameter.
 5. The fabric of claim 1, wherein said fabric is produced by a warp knitting process.
 6. The fabric of claim 1, wherein said loop pile construction is produced by a process selected from the group consisting of napping, overfeeding of the yarns, pressing off, and yarn manipulation.
 7. The fabric of claim 1, wherein said loop pile construction is produced by a napping process.
 8. The fabric of claim 1, wherein the filament yarns have a tenacity of between about 4 and 7 grams/denier.
 9. The fabric of claim 1, wherein the filament yarns have a filament denier of between about 40 and
 70. 10. The fabric of claim 9, wherein the number of filaments per yarn of the filament yarns is between about 10 and
 24. 11. The fabric of claim 9, wherein the spandex yarns have a denier of between about 40 and
 70. 12. The fabric of claim 3, wherein the fabric has a widthwise stretch of between about 75% and 125% and a lengthwise stretch of between about 25% and 60%.
 13. The fabric of claim 1, wherein the mesh construction of the fabric defines a plurality of openings having a widthwise mesh count of between about 5 and 18 meshes/inch and lengthwise mesh count of between about 4 and 6 meshes/inch.
 14. The fabric of claim 10, wherein the spandex yarns have a denier of between about 40 and
 70. 15. The fabric of claim 13, wherein said plurality of openings each has a size between about 1 and 3 mm. in diameter.
 16. The fabric of claim 1, wherein: the filament yarns comprise nylon yarns; the fabric is produced by warp knitting; the loop pile construction is produced by a napping process.
 17. The fabric of claim 16, wherein the mesh construction of the fabric defines a plurality of openings having a widthwise mesh count of between about 5 and 18 meshes/inch and lengthwise mesh count of between about 4 and 6 meshes/inch.
 18. The fabric of claim 16, wherein the nylon yarns have a tenacity of between about 4 and 7 grams/denier.
 19. The fabric of claim 17, wherein the filament yarns have a filament denier of between about 40 and 70 and the spandex yarns have a denier of between about 40 and
 70. 20. The fabric of claim 19, wherein the spandex yarns have an elongation at break of between about 300% and 700%.
 21. A knit fabric comprising: filament yarns and spandex yarns integrally knit with the filament yarns; wherein the fabric has a mesh construction as well as a loop piles along one side thereof.
 22. A method for producing a fabric comprising: integrally knitting filament yarns selected from the group consisting of nylon yarns and polyester yarns with spandex yarns in order to produce a fabric with a mesh construction; and generating a loop pile along one surface of said fabric.
 23. The method of claim 22, wherein said loop pile is generated by a napping process. 